Government & Defence Entrance Exam

First of all, do not think that you are a average student, with strong dedication and hard work you can surely clear IAS or KAS exam.
Now to start preparation, as you have completed your 12th, you can start preparing for it form now on.
The UPSC (Union Public Service Commission) of India conducts the exam and on the basis of the result IAS, IPS, IFS officers are selected.
It has three-step process I.e.
Preliminary Exam (Prelims)
Main Exam (Mains), and
Interview.
For preliminary test preparation , you should be aware of all the current affairs, plus you should prepare well for general knowledge, you should develop a habit of reading news papers, magazines and journals daily, as this will help you to prepare well for GK and current affairs.
For mains you need to select your subject, you should always select those subjects in which you have maximum interest and liking, though most of the students form arts background opt for public Administration and Political Science,which ever subject you opt for you must have in depth knowledge of that.
It is one of the most competitive exams in India, to clear this exam you really need to work hard with 100% dedication.
To prepare well, it would be advisable to join some good coaching institute, so that you can get right guidance for preparation.
Find below some of the institutes for IAS preparation.
Rau's IAS,.
Chanakya.
Elite Academy.
Brilliant Tutorials.
Naraina ias academy.
To know the detailed information about the location, fee and class timing it would be advisable to personally visit these institutes and select the best institute.